91 golf stall while driving, will not start

I have a 91 Golf gl, digfant II. I was driving home from work today
and the engine sputtered down then died mid-drive. I drive a manual
and was able to coast into a parking lot. The oil pressure light was
flickering the entire time the engine was sputtering down. In the
parking lot I checked the oil, it was good. I tried restarting but it
would not turn over, it just turned and turned. I didn't smell
anything funny or see anything that was out of place (it was pretty
dark out, though).

I've had this symptom before and it turned out that I ecu and icm had
failed. I replaced both with a pair I pulled from a junkyard jetta
with same year and numbers. It's been running fine since (~6months
ago).

I'm going to check things out tomorrow when it's light out. I was
curious if anyone knew how to test the ecu or icm for failure. Also if
anyone has any other ideas as to what could be the culprit I'd be
greatly appreciate it.

thanks,
-Matt Johnson